The present invention relates to a driving gear for a rotor type, open end fine spinning machine, in which a spinning rotor is rotated at a high speed and friction heat produced by the rotation of the spinning rotor is removed.
A rotor type, open end spinning machine in the prior art has a driving gear in which a rotation shaft of a spinning rotor is connected to a motor by a belt transmission mechanism. Such a spinning rotor is rotated at a high speed greater than 40,000 r.p.m., since productivity of yarn is proportional to the rotational speed of the spinning rotor. When the spinning rotor is rotated at a high speed, however, the driving force for the spinning rotor increases because of weight of the spinning rotor itself, and the rotation load caused by air resistance increases the tension imposed on the belt of the transmission mechanism. In the above-mentioned driving gear, tension or vibration of the belt is transmitted directly to the rotation shaft of the spinning rotor, whereby the rotation shaft of the spinning rotor and a bearing thereof may be abraded severely and the rotational speed of the spinning rotor is limited thereby.
Another driving gear has been invented in which a number of small motors is coupled to corresponding ones of a like number of spinning rotors. However, such a driving gear requires a large number of the small motors, e.g. 100 to 200, to be coupled to a like number of the spinning rotors and therefore becomes expensive.
Another driving gear has been invented in which a disc roller is interposed between the rotation shaft of the spinning rotor and the belt connected to the motor. In such a driving gear, a space is required for the disc roller and the spacings between the spinning rotors are widened, whereby the spinning rotors which can be installed on the fine spinning machine are decreased in number and it is difficult to improve the productivity of one spinning machine.
In order to eliminate above-mentioned disadvantages in the prior art, the inventors have already invented a driving gear as set forth in U.S. patent application Ser. No. 413,547. In this driving gear, a drive shaft connected to a motor by a belt transmission mechanism and a rotation shaft of a spinning rotor are coupled through a speed multiplying mechanism comprised of a small planetary friction wheel mechanism so that the spinning rotor is rotated at a high speed with little vibration. However, as the rotational speed of the spinning rotor is increased, the amount of lubrication oil to be supplied to the speed multiplying mechanism must be increased, and the heat generation due to friction in the bearing of the rotation shaft of the spinning rotor and the speed multiplying mechanism, increases. Accordingly, the rotational speed of the spinning rotor is limited by the heat generation due to friction and increased productivity is also limited.